Q and A: Clock Hands – what are they for?

Q1 I read in your blog about the new algorithm with two clock hands to control memory consumption, but I really would like to understand exactly what the hands are doing and if they relate to the lazywriter. A1. In SQL Server 2005 we have separated database cache, Buffer Pool, and the rest of the…

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Q and A: Virtual Address Space, VAS, reservation – why bother?

Seems like today is a question day :-). I will attempt to answer several questions about VAS I got today: Q1.  There is one aspect of Virtual Memory that is just not clear yet. I think I understand about VAS, but maybe not as much as I could, but I don’t understand about ‘reserving memory’. When we talk about SQL…

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Q and A: x64 & AWE mechanism

  Today I received following question: Hello, We will be running Windows Server 2003 x64 with SQL Server 2005 x64.  I would think AWE would not come into the picture in this scenario. I’m trying to find out more about SQL Server 2005 memory management on x64 systems using x64 versions of the OS and…

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Be aware: To Hyper or not to Hyper

Our customers observed very interesting behavior on high end Hyperthreading (HT) enabled hardware. They noticed that in some cases when high load is applied SQL Server CPU usage increases significantly but SQL Server performance degrades. Occasionally they would also see message in errorlog indicating one of the threads can’t acquire a spinlock (Spinlock is a…

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Final changes in SQL Server 2005’s memory manager

As you would expect in the last several months SQL 2005 went through rigorous testing.  During the period we have identified and put several improvements that you might be interested to hear about.   Memory Broker Analyzing SQL Server’s behavior with respect to memory consumption from multiple sources we realized that we have an opportunity…

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